Metal rolling machine



May 3, 1960 T. GROB ETAL METAL ROLLING MACHINE 2 Sheets-Sheet 1 FiledNov. 9, 1956 FIGJ.

INVENTORS Ernst Grab BY Theodore Grab ATTORNEY T. GROB ET AL METALROLLING MACHINE May 3, 1960 2 Sheets-Sheet 2 Filed Nov. 9, 1956INVENTORS t Grab E Th ore Grab ATTORNEY Zurich, Switzerland ApplicationNovember 9, 1956, Serial No. 621,237 .2 Claims. (Ci. S d-23) Thisinvention relates to the art ofmetal rolling and particularly to arolling method and apparatus for the chipless production of spur andhelical gears, multiple splines and the like.

Prompted by the success had in the chipless production of screw threadsby rolling methods heretofore used,

various attempts have been made to utilize such methods in theproduction of articles of the type above named, but without success. Itwould appear that the higher lead ang es of the teeth or ribs,characteristic of such articles, 'introdutce problems heretoforeunsolved and render inapplicable thosethread rolling methods heretoforeknown.

One object of the present invention is to provide a rolling method andapparatus specially adapted for the accurate production of multiple ribsand grooves of high head angle on cylindrical blanks. This we haveaccomplished by passing the blank lengthwise between andin rollingengagement with a set of spaced forming rollers whose axes of rotationareslightly tilted relative to the blank axis so that the desiredlengthwise advance of the blank is induced by the rolling engagement ofthe rollers with the blank, and whose transverse contours .varyprogressively at successive points in the length 'of the rollers in amanner to determine the progress of the shaping action.

It has been found particularly favorable for the material structure ofeach tooth being formed if it is"not laterally confined by and betweenthe sides of adjacent United States Patent forming ribs whose actioncauses the tooth to expand 'or a rise outwardly as it is being formed.As a result of such confinement, undesirable folds develop in the tipsof the teeth, as in some thread rolling operations.

' Another object of the present invention is to avoid such folds. It hasbeen found that this objectionable condition may be avoided entirely orfor the most part by a forming action which causes each instant toothsection under treatment to be pressed up from the right and from theleft alternately so that the material thereof may deviate slightly abouta tilt point located in the vicinity of the root of the tooth. In theapparatus hereinafter described this is accomplished by providingrecesses or interruptions in alternate forming ribs, particularly in thezone of maximum deforming action.

Other more specific objects and advantages will appear, expressed orimplied, from the following description of an'exemplary method andapparatus whereinthe principles of the present invention areadvantageously utilized.

For purposes of explanation the invention will be described as appliedto the chipless production of spur gears whereby teeth of finished formare first developed, as

.ribs on cylindrical blanks of considerable length, and

which are later divided to provide gear units 'of desired face width;although, as above noted, the invention may grooves whose lead anglesare high. i ."I th aw nra y usfi ewin n "ice Figure 1 is a fragmentarylongitudinal sectional view illustrating the relative positions of blankand forming roller in a metal rolling machine embodying the presentinvention.

Fig. 2 is a fragmentary transverse sectional view including analternative form of blank guide.

Fig. 3 is a side view, partly in section, of a forming roller such asshown in Figs. 1 and 2, but equipped, with interrupted alternate formingribs. 7

Fig. 4 is a front end view of a-forming roller.

' Fig. 5 is a view similar to Fig. 3 illustrating a forming rollerequipped with a preliminary blank-gripping roller. Fig. 6 is'atransverse section and Fig. 7 a plan view of modified form of apparatusinvolving the use of 'a single roller of the form shown in the precedingfigures. Fig. 8 is a transverse section and Fig. 9 a longitudinalsection of a further modified form of apparatus embody= ing theinvention.

The apparatus shown in Figs. '1 and 2 comprises a pair of laterallyspaced rotary forming rollers 3 and 4 supported and driven in the samedirection and at the same peripheral speed by means and in a manner wellknown in the thread rolling art.

The space between the rollers constitutesa working zone through which .acylindrical blank W under treatment is continuously advanced lengthwisewhile in rolling engagement with both rollers. The blank W is centeredand guided in its advance by suitable guides, such as the alignedbushings 1 and 2 disposed fore and aft of the working zone, as indicatedin Fig. 1, or such as the spaced guide bars 5 and 6 shown in Fig. 2. Theopening in the rear bushing 2 is larger than that of the forward bushing1 to accommodate the increased diameter of the finished blank as itleaves the working zone, and the guide faces of the bars 5 and 6 of Fig.2 are" slightly inclined relative to-each other for the'same purpose. 7

The blank W is continuously rotated during its passage through theworking zone as a result of the continuous rolling engagement thereofwith the driven rollers; and the lengthwise advance of the blank throughthe working zone also results from the same rolling engagement, the axesof the rollers being oppositely tilted out of coplanar relation with theaxis of the blank for that purpose. The angle of tilt between the axisof roller 3 and the blank axis is indicated at X in Fig. l, and theangle of tilt between the axis of roller 4 and the blank axis is ofequal value but in an opposite direction. The degree of tilt determinesthe rate of advance of the blank relative to the rotative speed thereof,and it has been found that in most instances the best results areobtained witha small tilt angle, in the neighborhood of two degrees forinstance.

To insure that the blank W is rotating and advancing at the proper speedat the time of entry into the working zone, each forming roller may beequipped at its front or leading end with an auxiliaryfeed roller, suchas shown at 18 in Fig. 5, adapted to initially seize the blank andadvance it into the working zone. Each of these rollers may be equippedwith shallow ribs 18' respectively aligned with the forming ribs on theforming rollers, lor the peripheral surface thereof may be knurled orotherwise fashioned to insure gripping engagement Withthe blank.

Both forming rollers 3 and '4 are substantially identical so that adescription of one will sufiice for both. Each includes a taperedforming zone 7 and a cylindrical finishing zone 8. Each has formedthereon a circular series of helical forming ribs 9--10 each extendingacross the peripheral face of the roller and through both Zones 7 and 8thereof, and having a uniform predetermined lead angle, the degree oflead angle used and the shape ofthe insan ame @9 h article t b formalFor the production of straight spur gears, for instance, the formingribs are disposed with a lead angle X, as indicated in Fig. 3 equal toangle of tilt of the roller but of opposite hand, so that at each pointof engagement of a rib with the blank the rib extends parallel to theblank axis. For the production of helical gears, the forming ribs aredisposed with a lead angle greater or less than the lead angle of theteeth of the gear in an amount equal to the angle of tilt of the roller,dependent upon whether the gear to be produced is a helical gear of leftor right hand.

For the production of either straight or helical gears those portions ofthe forming ribs contained in the working zone 8 of a roller are shapedto mesh with those of the finished blank, just as though the roller andfinished blank were regular mating gears. The forming rollers arepreferably of greater diameter than the finished blank and are equippedwith forming ribs in greater number than the teeth in the finishedblank, but the rollers may be of the same size or smaller than thefinished blank and with ribs in equal or lesser number than the teeth ofthe finished blank.

The purpose and function of those portions of the ribs 9-10 contained inthe finishing zone 8 of the rollers is to calibrate the teeth in theformed blank and to finish the flanks thereof. The purpose and functionof those portions of the ribs contained in the forming zone 7 of therollers is to progressively develop teeth of desired form on the blankby a pure rolling action continuously applied as the blank advanceslengthwise through the working zone.

Those portions of the ribs in the forming zone 7 are shaped to mergesmoothly with those portions in the finishing zone 8, and they extendforwardly therefrom to the leading end of the roller with their outeredges slightly inclined inwardly, hence the tapered form of rollerwithin zone 7. This may be a straight taper or may be longitudinallycurved, either convexly or concavely, in order to properly distributethe forming load under various forming conditions. The taper is suchthat the external diameter of the leading end of each roller isapproximately equal to or slightly less than the pitch circle diameterof the gear-like formation of zone 8; and the axial extent of zone 7 maybe varied to best satisfy the requirements of any particular formingoperation.

It will be noted that, with the outer edges or crests of the ribs inzone 7 inclined in the manner above described, each is inclined withrespect to the blank axis during forming engagement thereof with theblank and in a direction to penetrate deeper into the blank as theforming engagement proceeds lengthwise of the engaged rib. In thisconnection it will be further noted that by reason of the helical formof each forming rib, no rib ever makes full length pressure contact withthe blank at any instant, such contact being limited to a zone oflimited length which travels or progresses lengthwise of the rib duringeach forming engagement of each rib with the blank. By reason of theseconditions the shaping pressures are highly concentrated, effective andefliciently applied, and the action is smooth and noiseless.

It will of course be understood that, as the rotating blank advancesfrom left to right (Fig. 1) to and between the forming rollers, it isinitially engaged by the inclined portions of the helical forming ribsof both rollers which act successively thereon to initially form thereina succession of recesses circumferentially spaced about the blank. Asthe advance continues, these recesses are extended and deepened byrepeated re-entry of the successive forming ribs thereinto and by therepeated shaping action of the ribs, this process continuing untilgrooves and intermediate ribs of desired shape are formed.

The inclined portions of the ribs in forming zone 7 of each roller maybe variously shaped in a manner best suited for any particular formingoperation. They may be shaped like the teeth of a slow tapered spiralbevel blank.

.4 gear, as indicated particularly in Fig. 4, or the spaces or groovesbetween the ribs may be parallel sided in which case the ribs would belongitudinally tapered. Or they might have a shape such as obtained byforming them on a roller initially of cylindrical form but ultimatelymachined into tapered form bya simple turning operation.

In order to avoid or reduce to insignificance the objectionable foldwhich commonly develops in the crests of ribs formed by rollingprocesses of the kind herein involved, suitable recesses, gaps orinterruptions, such as shown at 9" and 10', are provided in alternateforming ribs 9' and 10" of both forming rollers 3 and 4. These recessesare disposed within the forming zone 7 of each roller and particularlyin'regions of maximum forming action. The use of such recesses of courserequires that each roller be equipped with an even number of formingribs, and it is also important that a rotative phase relation bemaintained between the rollers such that an unrecessed rib 9 or 10 ofone roller always engages the same groove or tooth space on the blankwhich was last engaged by a recessed rib 10' or 9' of the other roller.The arrangement is such that throughout the shaping operation, each ribor tooth being formed on the blank is engaged on one side or the otheralternately by an unrecessed forming rib 9 or 10 on one or the otherroller and that, during each such engagement, each is also engaged onits opposite side by one of the recessed forming ribs 9' or 10' on thesame roller. A limited section of each rib or tooth being formed on theblank is thus capable of yielding slightly toward a recessed forming ribthroughout the forming action.

In the apparatus thus far described two forming rollers 3 and 4 areemployed,.although three or more may be used equally spaced about thecenter of the working zone. When such additional forming rollers areused, the blank is centered and guided thereby, thus eliminating theneed for guides such as shown in Figs 1 and 2.

The apparatus shown in Figs. 8 and 9 involves a three roller arrangementin which the forming rollers 3 have all of the structural and functionalcharacteristics of those included in the two roller arrangement ofFig. 1. In this instance, however, the non-travelling blank W isdirectly rotated by suitable means, such as a chuck 12, the rollers 3being rotated by the blank as a result of the rolling engagementtherewith, and the rollers being carricd by a suitable slide 14 fortravel lengthwise of the The slide is shown mounted for travel along apair of rigidly supported spaced guide bars 13-13 extending parallel tothe blank.

Each of the forming rollers 3 is shown suitably journalled on theprojecting end of a ram 15 guided for axial movement in a circular cage18 seated for rotary adjustment in the carriage 14. The longitudinalaxis of the ram 15 and cage 18 is disposed radially of the working zonebetween the rollers, and the ram is held against relative rotation withrespect to the cage 18 by splines 19 or the like. The desired angulartilt between each roller 3 and the blank is obtainable by rotativeadjustment of the cage 18, and each roller is held in proper workingrelation with respect to the blank by hydraulic pressure supplied to theouter end of the cage. A tail rod 20, extending through the outer end ofthe cage 18 and having nuts 21 threaded thereon, provides an adjustablelimiting stop for determining the proper working position of, eachroller with respect to the blank.

- 'The arrangement is such that upon relieving the hydraulic pressurefrom the outer ends of the cages 18 the several rollers 3 may beradially withdrawn sutficiently to admit entry of a blank therebetweenand into the driving chuck 12, and that by re-application of thehydraulic pressure the rollers may be advanced in proper workingposition. After each forming operation, the rollers may be againwithdrawn to permit withdrawal of the blank. A

At the start at least 0f each forming operation it is I" I! Am so as toinsure that the recesses initially formed in the blank be accuratelyspaced about the blank, and to insure re-entry of the forming ribs intothe recesses thus formed.

This is accomplished in this instance by an endless chain 16 trainedabout a series of sprockets 17. Some of these sprockets are connected toand rotatable with the rollers 3 while others are idler sprocketsyieldably supported to maintain tension in the chain. These othersprockets are shown supported on spring loaded rods 22 mounted andguided for lengthwise movement in the slide 14.

An'arrangement is shown in Figs. 6 and 7 in which a single formingroller 3 is used having all of the structural and functionalcharacteristics of that shown in Fig. 1.- It is shown journalled in asuitable support 23 and engaged with a blank W held in proper workingrelation therewith 'by'a pair of laterally spaced guide rollers 1111'which cooperate with the forming roller 3 to guide and center the blank.The guide rollers have teeth shaped to mesh with the tooth-like ribsformed by the forming roller. In this apparatus the blank is preferablymechanically rotated and all three rollers are rotatedby the blank andmounted for travel, as a unit, along the blank, in much the same manneras in the apparatus shown in Figs. 8 and 9. p

Various changes maybe made in any of the embodiments of the inventionhereinabove specifically described without departing from or sacrificingthe advantages of the invention as defined in the appended claims.

We claim:; t

1. In a metal rolling machine the combination of a pair of formingrollers disposed in spaced relationship to receive the cylindrical blanklengthwise therebetween and in rolling engagement therewith, the axis ofrotation of said rollers being tilted relative to the axis of theengaged blank to efiect a relative axial advance between said blank androllers by the rolling engagement therebetween, each of said rollershaving an even numbered series of circumferentially spaced parallelforming ribs rotation of the roller, each of said ribs having a blankpenetrating portion longitudinally inclined toward the V axis of theblank during engagement thereof with the a blank to effect aprogressively deeper penetration thereof in the blank during theengagement thereof with the blank, the sides of alternate ribs of eachforming roller having interrupted portions whereby the material of theblank engaged by the adjacent uninterrupted rib is permitted unimpairedlateral displacement within the range of theinterrupted side portions ofthe adjacent ribs, and the pair of forming rollers being arranged inphase relationship such that the uninterrupted ribs of one rollersuccessively engage the sides of the-teeth formed in the blank whichwere disposed adjacent the interrupted ribs of the preceding roller totherebyv overcome the formation of folds at the tip of the teeth whichnormally result when movement of the material of the blank is confinedbetween uninterrupted adjacent ribs.

2. In a metal rolling machine the combination of a pair of 'formingrollers disposed in spaced relationship to receive a cylindrical blanklengthwise therebetween and in rolling engagement therewith, each ofsaid rollers having a longitudinal tapered forming portion and acylindrical finishing portion coaxial therewith, the axis of rotation ofsaid rollers being oppositely tilted relative to the axis of the engagedblank to eifect relative axial advance between said blank and rollersibythe rolling engagement therebetween, each of said rollers having an evennumbered series of circumferentially spaced parallel forming ribsthereon successively engageable with the blank during rotation of therollers, each of said ribs having a blank penetrating portionlongitudinally inclined toward the axis of the blank during engagementthereof with the blank to efiect a progressively deeper penetrationthereof in the blank during its engagement therewith, the sides ofalternate ribs of each forming roller having interrupted portionswhereby the material of the. blank engaged by the adjacent uninterruptedrib is permitted unimpaired lateral displacement within the range of theinterrupted side portions of the adjacent ribs,

and the forming pair of forming rollers being arranged in phaserelationship such that uninterrupted ribs of one roller successivelyengage the sides of the teeth formed in the blank which were disposedadjacent the interrupted ribs oi the preceding roller to therebyovercome the formation of folds at the tip of the teeth which normallyresult when movement of the material of the blank is confined betweenuninterrupted adjacent'ribs in the forming portion of the roller, saidfinishing portion of the roller serving to complete the formation of theteeth.

Great Britain Sept. 20, 1944

